The timing for performing breast MR diffusion tensor imaging (DTI) is not restricted throughout the menstrual cycle, though the modulations in diffusion parameters due to hormone replacement therapy (HRT) and lactation should be taken into account in DTI evaluation, according to a study published in the June issue of Radiology.
Dynamic contrast material-enhanced (DCE) MRI is a valued tool for breast imaging, as its high sensitivity leads to breast cancer detection. However, hormone-induced changes in normal breast parenchymal enhancement have the potential to affect the accuracy of diagnosis and restrict the selection and timing of DCE examinations. Diffusion-weighted MRI is now used hand-in-hand with DCE MRI to improve diagnostic accuracy.
“Thus far, hormone-induced changes in diffusion MR imaging experiments were investigated only with preliminary DW imaging studies, which yielded conflicting results,” wrote lead author Noam Nissan, MD, of the Weizmann Institute of Science in Kfar Saba, Israel, and colleagues. “Our goal was to investigate the parameters obtained with DT imaging of the breast throughout the menstrual cycle phases, during lactation, and after menopause, in volunteers with and without HRT.”
The study included 45 healthy volunteers who underwent imaging by using a T2-weighted and DTI MR sequence at 3T. Sixteen premenopausal women underwent imaging weekly and four times during one menstrual cycle. Nineteen postmenopausal volunteers and ten lactating volunteers underwent imaging one time. The researchers calculated principal diffusion coefficients, apparent diffusion coefficient (ADC), fractional anisotropy (FA) and maximal anisotropy for the fibroglandular tissue in the entire breast.
Results indicated that in all premenopausal volunteers, the DTI parameters showcased high repeatability, remained almost equal along the menstrual cycle and had a low mean within-subject coefficient of variance of λ1, λ2, λ3, and ADC—all were between 1 and 2 percent. FA was five percent. There was also a high intraclass correlation of 0.92 to 0.98.
Diffusion coefficients were significantly lower in the group without HRT use in comparison with the group with HRT use and premenopausal volunteers. The coefficients were additionally lower in the lactating volunteers as compared with the premenopausal volunteers. No significant differences in DTI parameters were observed between premenopausal volunteers free of oral contraceptives and those who used them and between premenopausal volunteers and postmenopausal volunteers who used HRT.
“In summary, we found that breast DT parameters are not sensitive to menstrual cycle changes, whereas lactation and long-term use of HRT do not affect diffusion parameters,” wrote the authors. “Therefore, the timing for performing breast DT imaging is not restricted throughout the menstrual cycle, whereas the modulations in diffusion parameters due to HRT and lactation should be taken into account at DT imaging evaluation.”